U.S. patent application number 11/527268 was filed with the patent office on 2007-03-29 for tricarboxylic acid ester plasticizers and methods of making.
This patent application is currently assigned to Vertellus Performance Materials, Inc.. Invention is credited to Edward P. Frappier, Samuel W. Kennedy.
Application Number | 20070072988 11/527268 |
Document ID | / |
Family ID | 37900380 |
Filed Date | 2007-03-29 |
United States Patent
Application |
20070072988 |
Kind Code |
A1 |
Frappier; Edward P. ; et
al. |
March 29, 2007 |
Tricarboxylic acid ester plasticizers and methods of making
Abstract
A plasticizer formed by reacting a carboxylic acid with a
mixture of two or more alcohols that vary from one another by the
number of carbons comprising them. The carboxylic acid used may be
a tricarboxylic acid such as citric acid or any other carboxylic
acid. Further, the resultant ester formed by reacting the
carboxylic acid with the alcohol mixture may be acylated to form a
plasticizer having somewhat different characteristics. According to
the present invention, a plasticizer formed by any of the processes
described herein can be used in conjunction with polymers according
to methods well known in the art to increase pliability and
plasticity.
Inventors: |
Frappier; Edward P.;
(Kernersville, NC) ; Kennedy; Samuel W.; (Liberty,
NC) |
Correspondence
Address: |
ICE MILLER LLP
ONE AMERICAN SQUARE, SUITE 3100
INDIANAPOLIS
IN
46282-0200
US
|
Assignee: |
Vertellus Performance Materials,
Inc.
Greensboro
NC
|
Family ID: |
37900380 |
Appl. No.: |
11/527268 |
Filed: |
September 26, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60720626 |
Sep 26, 2005 |
|
|
|
60720627 |
Sep 26, 2005 |
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Current U.S.
Class: |
524/567 ;
524/296 |
Current CPC
Class: |
C08K 5/11 20130101 |
Class at
Publication: |
524/567 ;
524/296 |
International
Class: |
C08F 214/06 20060101
C08F214/06 |
Claims
1. A method of producing a plasticizer composition comprising the
steps of: a. providing an alcohol mixture comprising a first
alcohol having m carbons with a second alcohol having n carbons,
wherein m>n; b. reacting the alcohol mixture with a
tricarboxylic acid to form an ester.
2. A plasticizer formed by the method of claim 1.
3. The method of claim 1, further comprising the step of acylating
the ester.
4. The method of claim 1, wherein m-n>4
5. The method of claim 3, wherein n is an integer between 0 and
13.
6. The method of claim 4, wherein n<6 and m>8.
7. The method of claim 1, wherein the second alcohol is butanol and
the first alcohol is nonanol.
8. The method of claim 1 wherein the first alcohol is a branched
alcohol.
9. The method of claim 8 wherein the tricarboxylic acid is citric
acid.
10. The method of claim 1, wherein the alcohol mixture consists
essentially of the first alcohol and the second alcohol.
11. The method of claim 1, wherein the first and second alcohols
are combined in equimolar amounts.
12. The method of claim 1, wherein a ratio of alcohol mixture to
tricarboxylic acid is three moles to one mole, respectively.
13. The method of claim 1, wherein the tricarboxylic acid is
selected from the group comprising citric acid, trimellitic acid,
and aconitic acid.
14. The method of claim 1, wherein the tricarboxylic acid is in its
anhydrous form.
15. The method of claim 1, wherein the plasticizer composition
comprises a plurality of resultant ester species.
16. The method of claim 1, wherein: a. the first alcohol is
isononyl alcohol, b. the second alcohol is butyl alcohol, and c.
the tricarboxylic acid is citric acid, d. wherein the alcohol
mixture consists essentially of isononyl alcohol and butyl alcohol
in about equimolar amounts, and e. wherein the plasticizer
composition comprises a plurality of different ester species.
17. The method of claim 16 wherein the ester or ester species
comprises at least one moiety of the first alcohol and at least one
moiety of the second alcohol.
18. A composition produced by the method of claim 16.
19. A method of forming a plasticized polymer comprising the steps
of: a. providing an alcohol mixture comprising a first alcohol
having m carbons with a second alcohol having n carbons, wherein
m>n; b. reacting the alcohol mixture with a tricarboxylic acid
to form an ester; c. selecting a polymer; and d. combining the
plasticizer with the polymer to form a mixture.
20. The method of claim 20, wherein the plasticizer comprises at
least 15% by weight of the mixture.
21. The method of claim 21, comprising the additional step of
heating the mixture.
22. The method of claim 21, wherein the polymer is PVC, PVDC, or
vinyl.
23. A composition according to the method of claim 23, wherein the
plasticizer displays a permanence in the range of about 13% weight
loss to about 35% weight loss.
Description
CLAIM OF PRIORITY
[0001] The present application claims priority to U.S. Provisional
Application Ser. Nos. 60/720,626 for Citrate Acid Ester
Plasticizers and Method of Making and 60/720,627 for Trimellitic
Acid Ester Plasticizers and Method of Making, filed Sep. 26,
2005.
BACKGROUND
[0002] The present invention generally relates to the field of
polymers. Specifically, the present invention relates to
plasticizers used in polymers to create desired physical
characteristics in the resulting polymer/plasticizer complex, such
as increasing flexibility, pliability and plasticity in the
resultant polymer complex. For example, plasticizers such as
di(2-ethylhexyl)phthalate ("DEHP"), di-isononyl phthalate ("DINP"),
and other phthalate plasticizers have long been industry standard
plasticizers used with polymers such as homo- and copolymers--of
polyvinyl chloride ("PVC"), polyvinyl dichlorides ("PVDC"), vinyls,
and similar polymers and resins to impart pliability and plasticity
while retaining good tensile strength, and resistance to cracking
at low temperatures. For example, phthalate plasticizers have been
used with rigid polymers such as PVC to create pliable materials
used in such goods as intravenous (IV) bags and tubing, molded
children's toys that require a soft or malleable feel, and various
other applications where pliability or softness needs to be
imparted to a polymer. Phthalate plasticizers such as DEHP and DINP
were once preferred plasticizers due to their ability to impart the
physical characteristics noted above, and their permanence in the
polymer over time, even when exposed to relatively high
temperatures and humidity.
[0003] However, public sentiment has prompted many manufacturers of
consumer products to discontinue use of phthalates as a plasticizer
due to concerns over potential adverse health effects. Thus,
plasticizer compositions that reduce or eliminate phthalates, but
perform similarly to DINP or other effective phthalate
plasticizers, would be greatly appreciated in the art. Attempts
have been made to supply a replacement for phthalate plasticizers,
such as the use of acetyl tributyl citrate ("ATBC"), sold by
Vertellus Performance Materials, Inc., of Greensboro, N.C. While
ATBC has been found to be an effective substitute for phthalates
such as DINP, improved permanence in polymers such as vinyls, PVCs,
and PVDCs is desired. It is believed that permanence may be
improved by replacing the low molecular weight butyl citrate ester
chains with longer chain substituents. However, tests using long
chain citrate esters such as acetyl trioctyl citrate and acetyl
tridecal citrate have shown these long chain citrate esters to be
poorly compatible or incompatible with many polymers, especially
when used in the concentrations required for rotational molding of
products such as children's toys, or in the production of polymer
sheeting or films such as those used in the production of bags for
administering intravenous pharmaceuticals. Thus, simply increasing
the chain length of substituents has not proven to be a viable
option for increasing permanence in a non-phthalate plasticizer, as
in many plastisols.
[0004] Other attempts to increase permanence in non-phthalate
plasticizers include the creation of mixed species of citrate
esters formed by reacting commercially available side streams of
mixed longer chain alcohols (specifically mixtures of hexanol,
octanol, and decanol, and mixtures of octanol and decanol) with
citric acids, and thereafter acetylating the resultant ester.
Unfortunately, these mixed species of esters have also shown poor
compatibility with some polymers, particularly when the plasticizer
is used at a level above 20% of the resultant
polymer/plasticizer.
[0005] Therefore, alternative non-phthalate plasticizers, which
show an improved permanence in, and high compatibility with, a
broad range of polymers would be greatly appreciated in the
art.
SUMMARY
[0006] The present invention relates to plasticizer systems, their
method of making, and use thereof. According to one aspect of the
present invention, a novel plasticizer may be formed by reacting at
least two different alcohols with a tricarboxylic acid. In one
embodiment, the two alcohols vary from one another in their carbon
content by at least four carbons. In another embodiment of the
present invention, the tricarboxylic acid selected is citric acid.
Further, it should be noted that optionally the citrate esters
formed by the method discussed above may be acylated to create
plasticizers with slightly different properties.
[0007] For clarity, it will be appreciated that the selection of
two alcohols used in the present invention may be selected by
expressing the number of carbons in the first alcohol as m, and the
number of carbons in the second alcohol as n, wherein m-n>4.
Further, according to one aspect of the present invention, the
alcohols selected might be limited to the number of atoms by
defining n as an integer greater than 0 and less than 13.
[0008] According to another embodiment of the present invention, a
plasticizer formed according to the methods detailed above may be
used to form a plasticized polymer by adding any plasticizer formed
by the method or combination of methods outlined above and
combining the plasticizer with a selected polymer to form a
mixture. Optionally, the mixture may be such that the plasticizer
comprises at least 15% plasticizer by weight.
DESCRIPTION
[0009] The present invention relates to compositions of
plasticizers used to produce plastics having desired flexibility,
pliability and plasticity, a method for making the plasticizers,
and a method for using the plasticizers.
[0010] The polymer industry has been searching for an alternative
to phthalate based plasticizers such as the previous industry
standard DINP. However, creating a non-phthalate plasticizer with
similar physical properties such as pliability or efficiency
(measured in Shore A Hardness) imparted to the polymer, low
temperature crack resistance, tensile strength, tensile elongation,
retention or permanence of the plasticizer in the polymer mixture
over time, and resistance to water and high humidity has proven
difficult. The present invention presents novel compositions that
meet some or all of these properties.
[0011] In particular, the present composition relates to
plasticizer systems that are tailored to meet particular
requirements, illustratively having a high compatibility with the
polymers to which it is applied, and displaying an effective
permanence in the polymer mixtures comprising the plasticizer. For
example, one illustrative embodiment of the present invention
relates a plasticizer that displays plasticizing qualities
comparable to that of DINP, although that plasticizer does not
comprise phthalate. Illustratively the plasticizer displays a
permanence of no more than 30% loss of the plasticizer from the
plasticizer/polymer mixture over a 28 day period when exposed to a
temperature of 70 degrees Celsius. More illustratively, the
permanence displays no more than 25% loss of the plasticizer in the
28 day period, and exemplary about 18% loss.
[0012] Specifically, one embodiment of the present invention
relates to a plasticizer formed by the reaction of at least two
different alcohols with a carboxylic acid (e.g., a tricarboxylic
acid such as citric acid, aconitic acid) or its anhydride.
Illustratively, the alcohol species vary in the number of carbon
atoms comprising them by more than four carbon atoms (e.g., butanol
and nonanol, which vary by five carbon atoms). In another other
embodiment, the resultant esters formed above are then acetylated
by a method well known in the art, such as adding acetic anhydride
to the esters, thereby forming an acetylated ester.
EXAMPLE I
[0013] In one exemplary embodiment, not intended to limit the
embodiments discussed above, citric acid is reacted with equimolar
portions of n-butanol and isononyl alcohol. Thus, for example, two
moles (2M) of citric acid may be reacted with three moles (3M) of
n-butanol and three moles (3M) of isononyl alcohol to form two
moles (2M) of a plasticizer according to the present invention. It
will be appreciated that various mixtures of the molar ratios of
the alcohol will result in a different proportions of the mixed
ester. For example, in alternate embodiments, when 1M of the
tricarboxylic acid used, the alcohols used in the reaction are
added in a molar ratio such that they are combined to form 3M of
alcohol. For example, if 1.25 M of N-Butanol is used, 1.75 M of
second alcohol (said second alcohol having more than 4 carbons than
butanol e.g. octanol, nonanol, decanol, etc.) is use.
Alternatively, if 1.5 M butanol is used, 1.5 M of the second
alcohol is used; if 1.6 M of butanol is used, 1.4 M of the second
alcohol is used; if 1.75 M of butanol is used, 1.25 M of the second
alcohol is used; if 2.0 M of butanol is used, 1.0 M of the second
alcohol is used; if 2.2 M of butanol is used, 0.8 M of the second
alcohol is used; if 2.4 M of butanol is used, 0.6 M of the second
alcohol is used; if 2.6 M of butanol is used, 0.4 M of the second
alcohol is used; if 2.8 M of butanol is used, 0.2 M of the second
alcohol is used. Likewise, as discussed above, any ratio of the two
selected alcohols may be used, with the preferred overall molar
ratio of tricarboxylic acid to the combined alcohols is
approximately 1:3. Optionally, the resultant plasticizer is then
acetylated by means well known in the art (e.g., reaction of the
plasticizer with acetic anhydride). The resultant plasticizer is a
mixture of several species of acetyl tricarboxylic citrates. In the
above example utilizing N-Butanol and Isononyl alcohol, the
plasticizer is a mixed ester comprising acetyl tri-n-butyl citrate,
acetyl tri-isononyl citrate, acetyl di-n-butyl, monoisononyl
citrate, and acetyl mono-n-butyl, di-isononyl citrate
(collectively, the "Mixed Ester").
[0014] As shown in table 1, the mixed ester formed in the above
example has been shown to produce closer physical performance
results to that of DINP than a single acetyl tricarboxylic acid
ester (such as acetyl tri-n-butyl citrate) or a physical blend of
two such acetyl tricarboxylic acid esters (such as a physical blend
of acetyl tri-n-butyl citrate and acetyl tri-isononyl citrate). For
example, as shown in Table I below, the mixed ester plasticizer
displays a permanence in the polymer mixture that is nearly double
that of other non-phthalate plasticizers without a loss of other
desirable properties. Further, the plasticizer described in the
example produces plasticized plastics that exhibit superior
resistance to water and humidity. TABLE-US-00001 TABLE 1 Mixed
Ester From Acetyl Example Tri-n-butyl Physical (n-butanol/
Property/Plasticizer DINP Citrate Blend** isononyl alcohol) Tensile
Strength 2157 2300 2267 2267 (PSI) Ultimate Elongation 380% 379%
348% 356% (%) Low Temperature -64.5.degree. -57.5.degree.
-49.5.degree. -59.5.degree. Cracking (.degree. Celsius) Permanence
(% loss 7.4% 64.1% 33.5% 18.2% of plasticizer in 28 days at 70
Celsius) *All results tested at 40% plasticizer (by weight), used
with PVC as the polymer (Geon 121A resin used in this example,
available from PolyOne Corporation, Lemont, Illinois) and 3%
stabilizer (Mark 3023 stabilizer used in this example, available
from Chemtura, Germany). **Acetyl Tri-n-butyl Citrate and Acetyl
Tri-isononyl Citrate
[0015] Further, the mixed ester plasticizer formed by the process
outlined above displays a compatibility with polymers that is not
shown with the formation of a mixed ester plasticizer made by the
mixture of commercially available mixed alcohols such as octanol
and decanol ("C8-10") or hexanol, octanol, and decanol ("C6-10").
Thus, selection of alcohols according to the present invention
results in a plasticizer with better compatibility with polymers
than previous plasticizers made using commercially available mixed
alcohol streams. For example, one will appreciate that use of
branched alcohols with a carbon chain larger than 8, such as
isononal alcohol, isodecal alcohol may improve compatibility with
long chain plastics such as PVC. Further, current testing indicates
that permanence of the mixed ester according to the present
application may show even better comparative permanence when
compared over a longer period of time and under less extreme
temperatures.
[0016] One of ordinary skill in the art will appreciate that
tricarboxylic acids other than citric acid (such as aconitic or
trimellitic acid) may be used to create a plasticizer system, and
several combinations of alcohols may be used. For example, three
alcohols, each varying from one another in their carbon content,
may be combined with a tricarboxylic acid. In our example, the
ratio of the three alcohols to one another varies, but the overall
molar ratio of tricarboxylic acid to alcohol is about 1:3.
Optionally, excess alcohol may be used to drive the reaction.
Further, one of ordinary skill in the art will appreciate that at
least two alcohols combined with a carboxylic acid need not be
mixed in an equimolar ratio to one another. It is understood that
varying the chain length of the alcohols and varying the ratio of
alcohols to one another allows one to alter the resultant species
in the plasticizer to obtain a desired property.
[0017] According to comparative studies with plasticizers created
according to the present application as discussed above, Table 2
below summarizes the properties of a plasticizer according to the
present application when comparing the acetylated form with the
non-acetylated form. For comparison, acetyl tri-n-butyl citrate and
DINP were also tested using similar percentages as disclosed below.
TABLE-US-00002 TABLE 2 Acylated Non-Acylated Mixed Ester Mixed
Ester From Example (n-butanol/ (n-butanol/ Acetyl isononyl isononyl
Tri-n-butyl alcohol) alcohol) Citrate DINP Hardness, 68.9 68.7 64.7
67.7 10 sec Tensile 1914 2154 2012 2056 Strength, psi Ultimate 285
331 349 351 Elongation, % Brittle Point, -59.3 -62.3 -53.5 <68.5
.degree. C. Volatile Loss, 7.69 7.33 8.01 6.40 Air Water Ext. 2.28
1.62 1.53 1.26 Soapy Water 4.11 3.79 3.55 1.95 Ext Oil Ext 52.73
41.46 42.43 42.94 * All results tested at 40% plasticizer (by
weight), used with PVC as the polymer (Geon 121A resin used in this
example, available from PolyOne Corporation, Lemont, Illinois) and
3% stabilizer (Mark 3023 stabilizer used in this example, available
from Chemtura, Germany).
[0018] It will be appreciated that the water extract and soapy
water extract of the acetylated mixed ester performed within a
range comparable to DINP, while having the lowest brittle point and
a low volatile loss in air. Further, the non-acetylated form
performed in a usable range for possible applications.
[0019] Upon mixture of the components into a plastisol, the
viscosity of the mixtures was measured at time 0 and time 24 as
shown below for comparison in Table 3 below. It will be appreciated
that the viscosity for both the acylated and non-acylated forms
performed comparably to DINP, indicating its utility as a
replacement therefore. TABLE-US-00003 TABLE 3 Acylated Non-Acylated
Mixed Ester Mixed Ester From Example (n-butanol/ (n-butanol/ Acetyl
Viscosity isononyl isononyl Tri-n-butyl at Time alcohol) alcohol)
Citrate DINP Time 0 2520 2448 2604 2112 24 Hours 3048 2944 2880
3080
[0020] Table 4 below summarizes yet another embodiment of the
present application wherein a plasticizer according to the present
application is mixed with a PVC resin and a stabilizer. In the
study summarized in Table 4, a Geon 110.times.500 PVC resin
(available from PolyOne Corporation, Lemont, Ill.) was mixed at 65%
by weight with 32% by weight of the disclosed plasticizers, and
with 3% Synpron 1321 stabilizer. As shown below, both the
acetylated and non-acetylated forms of the plasticizers performed
within an similar range of DEHP, a plasticizer commonly used in
pharmaceutical fluid bags such as blood bags or intravenous fluid
bags and medical tubing, and performs as well as or better than
some DEHP alternatives (such as n-Butyryltri-n-hexyl Citrate and
Acetyl Tri-n-butyl Citrate) in certain applications. Further, as
shown below, the plasticizers according to the present application
further showed a good performance with regard to soapy water
extract percentages, as a reasonable amount of withdrawal of the
plasticizer into a blood bag extends the life of red blood cells
contained in the bag. TABLE-US-00004 TABLE 4 Acylated Non-Acylated
Mixed Ester n- Mixed Ester From Example Butyryltri- Acetyl
(n-butanol/ (n-butanol/ n-hexyl Tri-n-butyl Property isononyl
alcohol) isononyl alcohol) Citrate Citrate DEHP Hardness, Shore A,
10 sec 82.6 80.8 80.8 78.5 77.7 Tensile Strength, psi 2587 3122
2767 2740 2684 Ultimate Elongation, % 226 306 331 284 300 *Brittle
Point, .degree. C. -47.5 -45.5 -42.5 -38.5 -44.5 Air Volatility, %
pl loss 1.28 1.22 0.50 2.10 0.85 Water Ext, % pl loss 0.51 0.27
0.19 0.34 0.01 Soapy Water Ext, % pl loss 1.84 1.30 0.45 1.53 0.49
Oil Ext, % pl loss 29.5 17.0 22.2 21.4 18.9
[0021] In addition, the non-acylated mixed ester using butanol and
nonanol has been shown to have a fusion time of 2 minutes, 22
seconds when using a Brabender PL-2100 and 60 mL bowl to mix the
components. This is in comparison to a time of 1 minute, 37seconds
for n-butyryltri-n-hexyl citrate, 25.3 second for acetyl
tri-n-butyl citrate, and 36.7 seconds for DEHP. However, the
acylated mixed ester according to the present application has been
shown to have a fusion time of 34 seconds, which is even faster
than the previous industry standard plasticizer.
EXAMPLE II
[0022] According to another embodiment of the present invention, a
plasticizer formed by any of the methods described above is added
to a polymer to increase pliability and plasticity in the polymer.
For example, a plasticizer formed according to any of the methods
above is used as a replacement to a phthalate plasticizers. In one
exemplary embodiment, a plasticizer formed according to any of the
methods above may be added to a polymer to form a mixture of
approximately 15%-20% by weight plasticizer and a majority of the
remainder of the mixture comprising one or more polymers or resins
by weight to form a polymer mixture suitable for injection molding.
The method of combining said plasticizer and the polymers and
resins may be achieved by any one of the many methods well known in
the art.
[0023] For example, illustratively, a mixture of 15%-20% by weight
plasticizer with the balance comprising one or more polymers or
resins such as homo- or copolymer-PVC, PVDC, or vinyl may be used
in injection molding processes to produce children's toys.
EXAMPLE III
[0024] According to another embodiment of the present invention a
plasticizer as described above may be added to a polymer to form a
mixture of at least 20% by weight plasticizer (illustratively 20%
to 50% by weight) with a majority of the remainder of the mixture
comprising one or more polymers (illustratively PVC, PVDC, or
vinyls) or resins by weight to form a polymer mixture suitable for
rotational molding or preparation of sheet or film materials. The
method of combining said plasticizer and the polymers and resins
may be achieved by any one of the many methods well known in the
art, and may be used to create, for example, intravenous (IV)
pharmaceutical bags or rotationally molded toys such as a doll
head.
[0025] In fact, at least one citrate ester formed according to the
method described above has shown notable compatibility with
polymers, when compared to other non-phthalate plasticizers. The
compatibility of the plasticizer systems compositions described
herein have thus allowed the plasticizers to be used in greater
percentages by weight in polymer mixtures, allowing the use of
non-phthalate plasticizers in capacities where previous
non-phthalate plasticizers had proven unworkable.
[0026] Although the present invention has been described in
considerable detail with reference to certain preferred versions
thereof, other versions are possible. For example, one of ordinary
skill in the art will appreciate that different carboxylic acids
(including dicarboxylic acids and other molecules containing
multiple carboxylic acid groups) may be used to form plasticizers
according to the present invention. Further, alcohols may be
selected which have four or more carbon variances between them.
Additionally, the use of the resultant plasticizers may be used in
many other polymer applications. Therefore, the spirit and scope of
the appended claims should not be limited to the description of the
preferred versions contained herein.
* * * * *